JP5969236B2 - Ink discharge amount control device - Google Patents

Description

  The present invention relates to a line-type inkjet printer in which a line head in which a plurality of nozzles for ejecting ink are arranged in the main scanning direction is arranged for each color at intervals in the sub-scanning direction orthogonal to the main scanning direction.

  In the field of ink-jet printers, line-type ink-jet printers that enable high-speed printing by performing image formation (printing) in the main scanning direction in a so-called one-pass are becoming widespread.

  In this type of ink jet printer, a line head in which a plurality of nozzles for ejecting ink are arranged in the main scanning direction is used. In particular, in an inkjet printer capable of printing two or more colors, color-specific line heads are arranged at intervals in the sub-scanning direction orthogonal to the main scanning direction.

  A color image is formed on the printing paper by ejecting ink droplets from each nozzle of the line head when the printing paper passes below the line head of each color while conveying the printing paper in the sub-scanning direction. doing.

  By the way, in an inkjet printer, when a line head of a certain color is attached to be inclined with respect to the main scanning direction, an ink droplet of that color to be landed on the same pixel position of the printing paper together with ink droplets of other colors Misplaced and landed.

  When each color line head is composed of a plurality of head blocks arranged in the main scanning direction, even if some of the head blocks in a certain color line head are mounted inclined with respect to the main scanning direction. The landing position deviation occurs between the ink droplet of that color and the ink droplet of the other color.

  Such landing position deviation also occurs when the printing paper passes under the line head in a skew state inclined with respect to the sub-scanning direction. That is, when skew of the printing paper occurs, the paper width direction of the printing paper is inclined with respect to the main scanning direction. At this time, the relative positional relationship between the printing paper and the line head (or head block) is exactly the same as when the line head (or head block) is mounted inclined with respect to the main scanning direction. Therefore, the skew of the printing paper causes a landing position shift between the ink droplets of each color.

  The above-described deviations in the landing positions of the ink droplets of the respective colors are continuous as a phenomenon inherent to individual ink jet printers for any reason except for the skew of the printing paper caused by consumables such as a decrease in the transport roller. Appear in

  If the landing positions of the ink droplets of the respective colors are shifted, there arises a disadvantage that the color of the pixel has a different hue from the original color. Therefore, by controlling the timing of ejecting ink droplets from the nozzles for a specific color or changing the nozzles ejecting ink droplets of a specific color according to the inclination of the line head with respect to the conveyance direction of the printing paper It has been proposed to eliminate the deviation of the landing positions of the ink droplets of each color (for example, Patent Document 1).

JP 2009-23122 A

  In the above-described proposal, by utilizing the fact that the nozzles of each color corresponding to the same pixel are arranged adjacent to the same line head, the ink for each color is controlled by controlling the ejection timing of the ink droplets or changing the ejection nozzle. Displacement of the landing position of the droplet is eliminated. Therefore, when the nozzles of the respective colors corresponding to the same pixel are arranged apart from each other in the conveyance direction of the printing paper as in the case of an ink jet printer in which the line head is configured for each color, the color-specific inks can be obtained by the above-described proposed method. It is difficult to eliminate the landing position deviation of the droplets.

  The present invention has been made in view of the above circumstances, and the object of the present invention is continued in line-type inkjet printers due to factors inherent to the apparatus such as skew feeding of printing paper and attachment errors of line heads for some colors. It is an object of the present invention to provide an ink discharge amount control device that can appropriately eliminate a change in hue due to a landing position deviation of ink droplets for different colors.

In order to achieve the above object, an ink discharge amount control apparatus according to the present invention described in claim 1 comprises:
A print head that is provided with a plurality of nozzles and arranged so as to extend along the main scanning direction is arranged for each color at intervals in the sub-scanning direction orthogonal to the main scanning direction, and is conveyed in the sub-scanning direction Ink ejection amount control of an ink jet printer that forms a color image including at least two or more chromatic colors on the printing paper by landing ink droplets from corresponding nozzles of the line heads of the respective colors on the same pixel of the paper In the device
The printing paper based on at least one of the inclination of the extending direction of the line head with respect to the main scanning direction or the sub scanning direction and the inclination of the conveyance direction of the printing paper with respect to the main scanning direction or the sub scanning direction. Position misalignment information setting means for setting position misalignment information indicating the content of landing position misalignment between ink droplets of each color with respect to the same pixel;
A discharge amount correction table in which the landing position misalignment content and the ejection amount correction content of each color ink droplet for reducing the change in color tone of the pixel due to the landing position misalignment of the landing position misalignment content is stored. Storage means;
The discharge amount correction content of the ink droplets by the nozzles of the line head of each color is determined from the discharge amount correction table based on the positional shift information set in the positional shift information setting unit for each color and determined. A discharge amount correcting means for correcting the discharge amount of ink droplets by each nozzle of the line head of each color in the correction content;
It is characterized by providing.

In addition, the ink discharge amount control device according to the first aspect of the present invention further includes the line head corresponding to each of three or more chromatic colors, and the discharge amount correction table corresponds to the print paper. against the ink droplets chromatic no landing position deviation, relative the landing positional shift the contents of the ink droplets for other chromatic color is landing position deviation of the printing paper, the other chromatic color ink The table is associated with the discharge amount correction content of the droplet.

Furthermore, the ink discharge amount control device of the present invention described in claim 2 is the ink discharge amount control device of the present invention described in claim 1 , wherein the discharge amount correction table indicates a landing position for a color having a lower luminance value. The table is characterized in that the correction content of the ink droplet ejection amount with respect to the displacement amount is large.

According to a third aspect of the present invention, there is provided the ink discharge amount control device according to the first aspect of the present invention, wherein the storage means is configured to discharge the discharge amount according to the type of the printing paper. A correction table is stored, and the discharge amount of the ink droplets by each nozzle of the line head of each color with the correction content determined from the discharge amount correction table corresponding to the type of the printing paper by the discharge amount correction unit It is characterized by correcting.

Furthermore, the ink discharge amount control device of the present invention described in claim 4 is the ink discharge amount control device of the present invention described in claim 1, 2, or 3 , wherein the line head has a plurality of the nozzles. A plurality of blocks are arranged side by side in the main scanning direction, the positional deviation information setting means is configured to set the positional deviation information for each color in units of the head blocks, and the ejection amount correction means includes the head block. The ink droplet ejection amount of each nozzle of the line head of each color is corrected in units of the nozzle block with the ink droplet ejection amount correction content determined based on the unit positional deviation information. To do.

  In the line-type ink jet printer to which the present invention is applied, if there is a line head that is not arranged in the correct position among the line heads of each color, the ink droplets land on a part of the ink droplets of each color formed on the same pixel. Misalignment occurs. Further, even when the printing paper is conveyed in a skew state inclined with respect to the sub-scanning direction, landing position deviation occurs between ink droplets of each color on the same pixel. When such a positional shift occurs, the color tone of the image formed on the pixel changes from the color tone of the image to be originally formed.

  According to the ink ejection amount control apparatus of the present invention described in claim 1, the position deviation information indicating the positional deviation amount of the dots by the ink droplets of the respective colors formed on the same pixel corresponds to the pixel. The correction content of the discharge amount of each color ink droplet is specified using the discharge amount correction table stored in the storage unit, and the discharge amount of the ink droplet from the nozzle is corrected by the correction content.

  Therefore, some line heads of each color are attached to be inclined with respect to the main scanning direction X, or the printing paper is skewed with respect to the sub-scanning direction Y, and the ink liquid of each color for the same pixel. Even if the landing position deviation occurs between the droplets, it is possible to effectively suppress a change in the hue of the pixel.

Further, according to the ink discharge amount control device of the present invention described in claim 1 , when three or more chromatic colors are used, the ink droplets of the other two colors are generated for one color. The landing position shifts in the same direction, the landing position shifts in a different direction, and the landing position shift pattern becomes complicated.

Therefore, the discharge amount correction table accordingly, against the ink droplets chromatic no landing position deviation of the printing paper, the relative impact of the ink droplets for other chromatic color is landing position deviation of the printing paper By defining the contents of the positional deviation, it is possible to more accurately suppress the change in hue in the pixel due to the landing positional deviation generated between the ink droplets of each color on the same pixel.

Furthermore, according to the ink discharge amount control apparatus of the present invention as set forth in claim 2, in Lee ink discharge amount control apparatus of the present invention as set forth in claim 1, as the luminance value is lower chromatic, other color inks It is noticeable when the landing position shifts with respect to the droplet.

  Therefore, in the discharge amount correction table, by changing the discharge amount correction content of the ink droplets as the luminance value is lower, the change in the hue of the pixel due to the displacement of the ink droplets of some colors is changed. Appropriate ejection amount correction according to the color (brightness) of the ink droplet with the landing position shifted can be appropriately suppressed.

According to the ink discharge amount control apparatus of the present invention described in claim 3 , in the ink discharge amount control apparatus of the present invention described in claim 1 or 2 , if the type of printing paper is different, ink droplets are landed. The dot gain on the selected pixel is also different. If the dot gains are different, the degree of conspicuousness of the ink droplets that are displaced in the landing position also changes.

  Therefore, by preparing a discharge amount correction table for each type of print paper and correcting the discharge amount, by selecting a table corresponding to the type of print paper in use and applying it to the discharge amount correction of ink droplets, It is possible to appropriately suppress the change in the hue caused by the deviation of the landing position of the ink droplets by correcting the ejection amount according to the type of printing paper.

Further, according to the ink discharge amount control device of the present invention described in claim 4 , in the ink discharge amount control device of the present invention described in claim 1, 2, or 3 , the line head is constituted by a plurality of head blocks. In this case, the inclination of the extending direction with respect to the main scanning direction may change in units of head blocks.

  For this reason, since the ejection amount correction table exists in units of head blocks, the ink droplet ejection amount correction contents corresponding to the nozzles of the head block whose extending direction is inclined with respect to the main scanning direction are displayed in the main scanning direction. On the other hand, it is possible to prevent unnecessary application to the nozzles of the head block whose extending direction is not inclined.

1 is an explanatory diagram illustrating a schematic configuration of a line-type inkjet printer to which the present invention is applied. FIG. 2 is an explanatory diagram illustrating an image forming path of the printer unit illustrated in FIG. 1 from the side. (A) is explanatory drawing which shows the head holder of FIG. 2 from the downward direction, (b) is explanatory drawing which expands and shows the side cross section of the head holder. (A) is explanatory drawing which shows the state in which the head block shifted and attached to the head holder of FIG. 2, (b) is explanatory drawing which shows the state of the landing position deviation of the ink droplet in that case. FIG. 3 is an explanatory diagram illustrating a state in which a printing sheet is conveyed obliquely with respect to the sub-scanning direction along the image forming path of FIG. It is a block diagram which shows the structure of the control system of the line-type inkjet printer of FIG. It is explanatory drawing which shows the discharge amount correction table memorize | stored in the external storage device of the line-type inkjet printer of FIG. It is explanatory drawing which shows the discharge amount correction table memorize | stored in the external storage device of the line-type inkjet printer of FIG. It is explanatory drawing which shows the discharge amount correction table memorize | stored in the external storage device of the line-type inkjet printer of FIG. It is explanatory drawing which shows the discharge amount correction table memorize | stored in the external storage device of the line-type inkjet printer of FIG. 2 is a flowchart illustrating a procedure when ink droplet ejection amount adjustment processing is performed on the line-type inkjet printer side in FIG. 1. 7 is a flowchart showing a procedure when a part of ink droplet ejection amount adjustment processing is performed on the client terminal side of FIG. 6. 7 is a flowchart showing another example of the procedure when the ink droplet ejection amount adjustment processing is performed on the client terminal side in FIG. 6.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Throughout the drawings, the same or equivalent parts and components are denoted by the same or equivalent reference numerals, and the description thereof is omitted or simplified.

  FIG. 1 is an explanatory diagram showing a schematic configuration of a line type ink jet printer to which the present invention is applied. As shown in FIG. 1, a line-type inkjet printer (hereinafter abbreviated as “inkjet printer”) 1 of this embodiment includes a scanner unit 101 that reads a document image on a document and outputs an image signal, and a scanner unit. A printer unit 102 that prints (records) a document image on a printing paper S (single side or double side) based on an image signal output from 101, a display 103 for various display inputs, and a control unit 10 for overall control. I have. The printing paper S used for printing the original image in the printer unit 102 is conveyed from the paper supply unit 105 to the paper discharge unit 109 via the printer unit 102.

  FIG. 2 is an explanatory view showing an image forming path CR1 in which image formation is performed from the side in the printer unit 102 of the ink jet printer 1 according to the present embodiment, and FIG. 3A is an upper side of the image forming path CR1. 2 is an explanatory view showing the head holder 500 of FIG. 2 arranged from below, and FIG. 3B is an explanatory view showing an enlarged side cross section of the head holder 500.

  The printer unit 102 of the inkjet printer 1 according to the present embodiment has a line head 110 that is an image forming unit for each color. As shown in FIG. 3A, the line heads 110 of the respective colors extend along the main scanning direction X and are arranged at equal intervals in the sub-scanning direction Y, respectively. The line head 110 for each color is configured by arranging a plurality of head blocks 110 a in the main scanning direction X.

  As shown in FIG. 2, the printing apparatus according to the present embodiment includes an image forming path CR1 as its transport path. In this image forming path CR1, the printing paper is printed by the platen belt 160 at a speed determined by printing conditions. S (see FIG. 1) is conveyed in the sub-scanning direction Y. Above the image forming path CR 1, the line heads 110 of the respective colors are arranged to face the platen belt 160, and the nozzles of the head blocks 110 a provided in the line head 110 are applied to the printing paper S on the platen belt 160. Ink of each color is ejected in line units, and a plurality of images are formed so as to overlap each other.

  More specifically, the image forming path CR1 includes a platen belt 160 that is an endless conveyance belt, a driving roller 161 that is a driving mechanism of the platen belt 160, a driven roller 162, and the like. A head holder 500 is provided above the image forming path CR1, and a head block 110a of the line head 110 of each color is held in the head holder 500.

  The platen belt 160 is moved around by the driving roller 161, slides in a range facing the head block 110a, and conveys the printing paper S. Specifically, the platen belt 160 is wound around a pair of driving rollers 161 and driven rollers 162 that respectively extend in the main scanning direction, and is circulated in the sub-scanning direction Y by the driving force of the driving roller 161. .

  The head holder 500 is a box having a head holder surface 500a on the bottom surface. The head holder 500 holds and fixes the head block 110a of the line head 110 of each color and has other functional parts for discharging ink from the head block 110a. Store as a unit. Further, the head holder surface 500a which is the bottom surface of the head holder 500 is disposed so as to be parallel to the transport path. A plurality of mounting openings 500b are arranged on the head holder surface 500a. Each mounting opening 500b is formed in the same shape as the horizontal cross section of the head block 110a. The plurality of head blocks 110a are inserted through the respective mounting openings 500b, and the discharge ports protrude from the head holder surface 500a.

  As shown in FIGS. 3A and 3B, a plurality of head blocks 110a are provided for each color of K (black), C (cyan), M (magenta), and Y (yellow). The head blocks 110a for the respective colors are arranged at intervals in the sub-scanning direction Y. The plurality of head blocks 110a for each color are arranged side by side in the main scanning direction X, and every other head block 110a is arranged by shifting the position in the transport direction. As a result, the distance between the nozzles (not shown) at the extreme ends of the two adjacent head blocks 110a matches the distance between the adjacent nozzles of each head block 110a.

  Each head block 110a can change the number of ink ejection drops. The dot density changes depending on the number of drops to be ejected (number of droplets). Note that the inkjet printer 1 of the present embodiment has a function of adjusting the drop size as the droplet amount. The droplet amount in the head block 110a can be adjusted by adjusting the driving voltage of the head block 110a.

  By the way, as described with reference to FIG. 2, the head blocks 110 a of the line heads 110 of the respective colors are attached to a common head holder 500. When the head block 110a is attached to the head holder 500 while being tilted from the main scanning direction X, the ink droplets ejected from the nozzles of the head block 110a land on the print paper S while being displaced from the corresponding pixel positions. To do.

  4A is an explanatory view showing a state in which the head block 110a is displaced and attached to the head holder 500 of FIG. 2, and FIG. 4B is an explanatory view showing a state of landing position deviation of ink droplets in that case. is there. For example, when a certain head block 110a is attached to the head holder 500 with an inclination with respect to the main scanning direction X as shown in FIG. 4A, ink droplets are ejected from the nozzles of the head block 110a. As shown in FIG. 4B, the landing position on the printing paper S shifts in the direction corresponding to the inclination.

  When such a landing position shift occurs due to a mounting position shift of the head block 110a in any chromatic line head 110, each pixel on the printing paper S corresponding to each nozzle of the head block 110a. , The hue changes from the original hue. The reason is that the chromatic ink droplets ejected from the nozzles of the head block 110a whose mounting position has shifted are landed with a deviation from the landing positions of the other chromatic ink droplets.

  When such a change in hue occurs in pixels corresponding to the nozzles of the head block 110a in which the mounting position of the chromatic color line head 110 is shifted, the mounting position shift in the other pixels, that is, the line head 110 of the same color. A color difference occurs between the pixels corresponding to the nozzles of the other head blocks 110a that are not.

  The change in color on the printing paper S caused by the deviation of the landing position of the ink droplets varies depending on the content of the landing position deviation of the generated ink droplets. The landing position deviation content is, for example, the landing position deviation amount of the ink droplet or the color (chromatic color) of the ink droplet that is displaced. In addition, when the landing positions of two or more chromatic color ink droplets are shifted, the landing position shifts include the landing deviation pattern (for example, the match / mismatch of the landing position shift direction for each color or the landing position shift for each color). Amount).

  In the above, the change (difference) in the hue of the image due to the mounting position shift of the head block 110a of each line head 110 has been described. However, the change in the color of the image also occurs when the printing paper S is conveyed while being skewed with respect to the sub-scanning direction Y along the image forming path CR1.

  FIG. 5A is an explanatory view showing a state in which the printing paper S is conveyed obliquely with respect to the sub-scanning direction Y along the image forming path CR1 in FIG. 2, and FIG. It is explanatory drawing which shows the state of landing position shift. In FIG. 5A, the head blocks 110a (of the line head 110) of each color (representing cyan (C) and magenta (M) as representative in the figure) are correctly attached along the main scanning direction X. It has been. However, the transport direction Z of the printing paper S is inclined with respect to the sub-scanning direction Y.

  When the printing paper S is skewed, as shown in FIG. 5B, ink droplets from the nozzles (not shown) corresponding to the same pixel from the head block 110a (of the line head 110) of each color are formed. On the printing paper S, they are misaligned and landed. As described above, when the landing positions of the ink droplets of the respective colors are shifted due to the skew of the printing paper S, the color of the pixel changes from the original color.

  As described above, when the mounting position of the head block 110a with respect to the head holder 500 is shifted or the printing paper S is skewed, a portion where the color of the image changes to an original one occurs. The image quality is impaired.

  Therefore, in the inkjet printer 1 of the present embodiment, the ejection amount of the ink droplets ejected from the nozzles according to the mounting position shift of the head block 110a with respect to the head holder 500 and the skew feeding of the printing paper S is set for each color line. Adjustment is possible by the control unit 10 in units of nozzles in the head block 110a of the head 110.

  FIG. 6 is a block diagram showing an electrical configuration of the control unit 10 of FIG. As shown in FIG. 6, an external interface unit 15 of a client terminal 14 to be described later is connected to the control unit 10 via an external interface unit 11. For this connection, for example, a 100BASE-TX wired LAN is used. From this client terminal 14, the control unit 10 receives a print job of a document image. This print job includes postscript data and print environment data. The control unit 10 generates raster data of the original image based on the received postscript data of the print job. The ink jet printer 1 causes the printer unit 102 to print a document image on the printing paper S under the conditions specified in the printing environment information of the print job.

  A display 103 is connected to the CPU 90 of the control unit 10. As shown in FIG. 1, the display 103 is disposed on the upper part of the inkjet printer 1. The display 103 is an input operation unit that allows a user to select and input a menu for converting the read image into electronic data or self-diagnosis when the inkjet printer 1 is used in a scanner mode in which the scanner unit 101 reads an image from the printing paper S. Can be used as

  As shown in FIG. 6, the control unit 10 of the inkjet printer 1 that causes the printer unit 102 to perform a printing operation includes a CPU 90. The CPU 90 controls the operations of the scanner unit 101 and the printer unit 102 in accordance with the contents input and set from the display 103 based on the program and setting information stored in the ROM 91.

  Note that the control unit 10 is provided with a RAM 92, and the menu selection content input from the display 103 is stored in the RAM 92 as needed. The RAM 92 is provided with a frame memory area. In this frame memory area, the original image raster data generated by the CPU 90 from the postscript data of the print job input from the client terminal 14 to the control unit 10 is temporarily output until it is output to the printer unit 102. Is remembered.

  The control unit 10 is provided with an external storage device 93. In the external storage device 93, the display 103, the printer engine of the printer unit 102, and the firmware of the scanner unit 101 are stored separately for each area to be used.

  Further, the external storage device 93 (corresponding to the storage means in the claims) stores a positional deviation information table and a discharge amount correction table.

  The positional misalignment information table, which is specific to the ink jet printer 1, describes the landing position misalignment between the ink droplets of the respective colors ejected from the nozzles of the respective color line heads 110 with respect to the same pixel of the printing paper S. It is a table defined in units of blocks 110a.

  The ejection amount correction table shows the ejection amount correction contents of the ink droplets of each color for reducing the hue change occurring in the corresponding pixel due to the occurrence of the landing position deviation of the landing position deviation described above. This table is defined for each misalignment.

  7 to 10 are explanatory diagrams showing a discharge amount correction table stored in the external storage device 93 of FIG. FIG. 7 shows a case where one of the chromatic colors magenta, yellow, and cyan is inclined with respect to the main scanning direction X in three cases (A) to (C). Show.

  In FIG. 7, in case (A), when the magenta head block 110a is tilted with respect to the main scanning direction X, the case (B) is for yellow head block 110a with respect to the main scanning direction X. The case (C) shows a case where the cyan head block 110a is inclined with respect to the main scanning direction X.

  In any case, basically, the larger the inclination of the head block 110a with respect to the main scanning direction X, the smaller the ink droplet ejection amount is reduced. In this embodiment, the ink droplet ejection amount is increased or decreased by increasing or decreasing the drive voltage of the head block 110a.

  However, in the case of magenta in the case (A), since the brightness is higher than cyan and the landing position deviation is less noticeable than in the case of cyan, the landing position deviation of the ink droplet is the pattern (1) having the smallest inclination. The change in color due to is small. Therefore, for the pattern (1), the ejection amount correction of the magenta ink droplet is not performed.

  In the case of yellow (B), which has a higher luminance than magenta, the luminance is higher than that of magenta and the landing position deviation is less noticeable than in the case of magenta. Is small in change in hue due to deviation of the landing position of ink droplets. Therefore, for the patterns (4) and (5), the discharge amount correction of the yellow ink droplet is not performed.

  For cyan in the case of the lowest luminance (C), the landing position deviation is the most prominent, so even in the pattern (7) having the smallest inclination, the change in hue due to the landing position deviation of the droplet is large. Therefore, in any of the patterns (7) to (9), the discharge amount correction of cyan ink droplets is performed.

  FIGS. 8 to 10 each show two cases in which the head blocks 110a of the other two colors except the reference color which is one of the chromatic colors are inclined with respect to the main scanning direction X, respectively. Yes.

  FIG. 8 shows a case where the reference color is cyan. In FIG. 8, in case (D), when the magenta and yellow head blocks 110a are inclined in the same direction with respect to the main scanning direction X, in case (E), the magenta and yellow head blocks 110a are the main. The case where it inclines in the different direction with respect to the scanning direction X is shown.

  FIG. 9 shows a case where the reference color is magenta. In FIG. 9, in case (F), the cyan and yellow head blocks 110a are inclined in the same direction with respect to the main scanning direction X. In case (G), the cyan and yellow head blocks 110a are main. The case where it inclines in the different direction with respect to the scanning direction X is shown.

  Further, FIG. 10 shows a case where the reference color is yellow. In FIG. 10, in case (H), the cyan and magenta head blocks 110a are inclined in the same direction with respect to the main scanning direction X, and in case (I), the cyan and magenta head blocks 110a are mainly used. The case where it inclines in the different direction with respect to the scanning direction X is shown.

  Although there are some differences in the correction amount, the basic direction of correction of the ink droplet ejection amount is the same as when only the head block 110a of each color shown in FIG. 7 is tilted. However, since the table is when the landing positions of two colors are shifted instead of a single color, the combined contents of the two colors where the landing positions shift, and the combined contents of matching / mismatching of the amount of deviation of the ink droplets of each color and the direction of deviation. Correspondingly, the contents (correction presence / absence, correction amount, etc.) of the ejection amount correction of the ink droplets of the respective colors are slightly arranged.

Note that the above-described ejection amount correction table defines a correction amount assuming a case where a maximum ejection amount of ink droplets is ejected to a certain pixel. Therefore, when the ink droplets ejected according to the actual print job are not the maximum ejection amount, the correction amount may be adjusted in accordance with the ejection amount of the ink droplets actually ejected.

  Furthermore, the above-described ejection amount correction table may be provided individually for each type of printing paper S. Thereby, it is possible to define the correction content of the ejection amount of the ink droplets corresponding to the dot gain on the printing paper S having different dot gains.

  Next, the positional deviation information table stored in the external storage device 93 is a table in which landing position deviation patterns of ink droplets of chromatic colors (magenta, yellow, cyan) generated in each pixel of the printing paper S are classified. It is. This table may be classified in units of head blocks 110a or in units of line heads 110 (each color). Or it can also classify by a nozzle unit.

  In the positional deviation information table, the landing of the patterns (1) to (9) and (11) to (40), in which the discharge amount correction contents of the ink droplets are defined in the discharge amount correction tables of FIGS. A landing position deviation pattern of ink droplets generated in pixels of the printing paper S is classified into any one of the position deviation patterns.

  For example, this positional deviation information table can be acquired for each inkjet printer 1 before shipping the inkjet printer 1 and stored in the external storage device 93 as a table. The contents of the position deviation information table, for example, the landing position deviation amount and landing position deviation of the ink droplets ejected from the nozzles of the head block 110a in the same row of each chromatic line head 110 excluding K (black), for example. This direction can be obtained from the printing result for the actual printing paper S.

  Further, the positional deviation information table may be updated when a new event occurs that causes a change in the landing position deviation pattern of each chromatic ink droplet, such as replacement of the head block 110a or the image forming path CR1. .

  The client terminal 14 is configured by a PC (personal computer) or the like, and includes a CPU 16 that executes various processes based on a control program stored in the ROM 17, a RAM 18 that functions as a working area of the CPU 16, a keyboard, An input unit 19 composed of a mouse or the like and an output unit 20 composed of a liquid crystal display or the like are provided.

  In addition to the external interface unit 15 described above, an external storage device 21 and a disk drive 22 are connected to the CPU 16. The external storage device 21 includes an application program storage area for generating document image data, a printer driver program storage area for the inkjet printer 1, a database area for document image data generated using the application program, In addition, a database area such as standard contents of the printing environment information in the printer driver program or contents customized by the user is secured. The print environment information is output to the control unit 10 as print information data in the print job.

  The CPU 16 activates the application program in the external storage device 21 in accordance with the activation request input from the input unit 19, and the document image data having the contents instructed by parameter input from the input unit 19 is activated. Generate on application program. The generated document image data is displayed and output at the output unit 20, and when a save request is input from the input unit 19, it is stored in the database area of the document image data in the external storage device 21.

  The document image data stored in the database area of the external storage device 21 is read from the external storage device 21 when a read request is input from the input unit 19 while the application program is running. The read document image data can be displayed and output on the output unit 20, or can be processed on the application program and regenerated as new document image data.

  Then, when a print command is input from the input unit 19 while the application program is running, the CPU 16 generates a print job for the original image to be printed, and sends the generated print job from the external interface unit 15 to the control unit 10. Is output to the external interface unit 11. This print job can be output to the control unit 10 by the CPU 16 executing a printer driver program stored in the external storage device 21.

  In addition, the CPU 16 reads various programs and data from the disk-shaped recording medium 50 such as an optical disk by the disk drive 22 of the client terminal 14 and installs (stores) them in the external storage device 21 or transmits them to the inkjet printer 1 side. Can do.

  Next, the procedure when the ink droplet ejection amount adjustment processing is performed on the ink jet printer 1 side of FIG. 1 will be described with reference to the flowchart of FIG. The flowchart in FIG. 11 shows processing performed by the CPU 90 of the control unit 10 shown in FIG. 6 executing a program stored in the ROM 91.

  As shown in FIG. 11, the CPU 90 first shows the landing position deviation amount of the ink droplets ejected from the nozzles of the head block 110 a in the same row of the line head 110 of each color with respect to the same pixel of the printing paper S. Based on the positional deviation information table, positional deviation information is acquired in units of each pixel (corresponding to each nozzle) of the printing paper S or in units of the head blocks 110a in the same row (step S1). Then, the acquired positional deviation information is set as information for adjusting the ejection amount of ink droplets (step S3).

  Next, the discharge amount correction content of the ink droplet corresponding to the set positional deviation information is obtained from the discharge amount correction table for each pixel (corresponding to each nozzle) of the printing paper S or for each head block 110a in the same row. Identify. In the present embodiment, it is assumed that the head block 110a has a shear mode (share mode) type nozzle, and the correction content of the drive signal (discharge drive signal) used for nozzle discharge drive is specified (step S5).

  Then, every time a print job is input from the client terminal 14 and an image is printed by the printer unit 102, the CPU 90 uses a drive signal with a voltage value corresponding to the correction content specified in step S5 to The nozzles provided in the head blocks 110a in the corresponding rows of the (black) and M (magenta) line heads 110 are respectively driven (step S7).

  As is apparent from the above description, in the present embodiment, step S3 in the flowchart of FIG. 11 is processing corresponding to the positional deviation information setting means in the claims, and step S5 in FIG. Step S7 is processing corresponding to the discharge amount correcting means in the claims.

  Each procedure shown in the flowchart of FIG. 11 described above is executed in the inkjet printer 1. Then, the corresponding nozzle is driven by a drive signal having a voltage value corresponding to the correction content. As a result, even if the head blocks 110a in the same row in the line heads 110 of the respective colors are attached so as to be displaced with respect to the head holder 500, between the ink droplets of the respective colors for the same pixel. It is possible to effectively suppress a change in hue in the image of the pixel due to the generated landing position deviation.

  Further, the printing paper S is transported obliquely in the sub-scanning direction Y along the image forming path CR1, and discharged from the nozzles of the head block 110a corresponding to the line head 110 of each color with respect to the same pixel of the printing paper S. Even if a landing position deviation occurs between the formed ink droplets, it is possible to effectively suppress a change in hue in the image of the pixel.

  When a printer server that stores font data and the like is provided between the client terminal 14 and the ink jet printer 1, each procedure shown in the flowchart of FIG. 11 may be executed in the printer server.

  In the embodiment described above, the adjustment of the ink droplet ejection amount is performed by correcting the voltage of the nozzle drive signal on the ink jet printer 1 side. However, correction for adjusting the ejection amount of ink droplets is added to the image data supplied as a print job from the client terminal 14 having the printer driver function to the ink jet printer 1 on the client terminal 14 side. You can also.

  Hereinafter, modified embodiments of the present invention having such a configuration will be described. FIG. 12 is a flowchart showing a procedure when a part of the ink droplet ejection amount adjustment process is performed on the client terminal 14 side in FIG. In the present embodiment, as shown in FIG. 12, the control unit 10 of the inkjet printer 1 performs steps S1 to S5 related to acquisition and setting of positional deviation information and specification of the ink droplet ejection amount correction content. The subsequent procedure is performed at the client terminal 14.

  Then, the CPU 90 of the control unit 10 transmits the specified ink droplet ejection amount correction content to the CPU 16 of the client terminal 14 having a printer driver function (step S9).

  Upon receiving the ink droplet ejection amount correction content, the CPU 16 specifies the correction content of each of the multi-value data of M (magenta), Y (yellow), and C (cyan) from the received correction content (step). S11). Each time a print job is generated, each chromatic color of the print image generated by using the printer driver function, that is, M (magenta), Y (yellow), C (cyan) multi-value data, Correction is performed with a level change amount corresponding to the correction content specified in step S11 of FIG. 12 (step S13). Then, after performing RIP processing by halftoning or a raster image processor as necessary, the image data (print data) of a print job is transmitted to the inkjet printer 1 (apparatus main body) (step S15).

  As is clear from the above description, in the present embodiment, step S3 in the flowchart of FIG. 12 is processing corresponding to the positional deviation information setting means in the claims, and step S5 in FIG. Steps S11 and S13 are processing corresponding to the discharge amount correcting means in the claims.

  By performing the printing of the image by the image data of the print job transmitted from the client terminal 14 through the above procedure with the inkjet printer 1, the same effect as in the case of the above-described embodiment can be obtained.

  In the modified embodiment described above, the correction content of the ink droplet ejection amount is determined on the inkjet printer 1 side, and based on this, the print data (multi-value data) corresponding to the correction content is determined on the client terminal 14 side. ) Level change. However, these may be performed on the client terminal 14 side.

  In that case, the positional deviation information table and the discharge amount correction table stored in the external storage device 93 of the ink jet printer 1 are also stored in the external storage device 21 of the client terminal 14 and are specific to the ink jet printer 1 corresponding to the printer driver. It is memorized as a table. These tables may be downloaded from the inkjet printer 1 and updated and stored in the external storage device 21 of the client terminal 14 every time a specific event occurs periodically or aperiodically.

  The flowchart of FIG. 13 shows the acquisition and setting of positional deviation information and the specification of the ink droplet ejection amount correction contents in steps S1 to S5 of FIG. 12 performed by the CPU 90 of the control unit 10 of the inkjet printer 1. As shown in the procedure, the CPU 16 of the client terminal 14 executes based on the positional deviation information table and the ejection amount correction table of the external storage device 21 (steps S21 to S25). Thereafter, the CPU 16 executes the procedure from step S11 to step S15 in FIG.

  As is clear from the above description, in this embodiment, step S23 in the flowchart of FIG. 13 is processing corresponding to the positional deviation information setting means in the claims, and step S25 in FIG. Steps S11 and S13 are processing corresponding to the discharge amount correcting means in the claims.

  Even when the inkjet printer 1 prints an image based on the image data of the print job transmitted from the client terminal 14 through the above-described procedure, the same effect as in the above-described embodiment can be obtained.

  In each of the above-described embodiments, the landing position deviation of the ink droplets of each color and the corresponding discharge amount correction content are determined for each head block 110a or nozzle unit of each color line head 110. However, the landing position deviation of the ink droplets of each color and the corresponding discharge amount correction contents may be determined for each color (line head 110).

  Accordingly, the present invention can be applied to the case where the line head 110 is configured by a single block in addition to the line head 110 configured by a plurality of head blocks 110a as in the above-described embodiments. . Further, when the plurality of head blocks 110a of the line heads 110 of each color are respectively accommodated in individual holders and attached individually, all the head blocks 110a of the line heads 110 of a certain color are in the main scanning direction X for each holder. The present invention can also be applied to a case where the projector is attached at an angle.

In each of the above-described embodiments, the inkjet printer 1 that performs full color printing using three chromatic colors of M (magenta), Y (yellow), and C (cyan) in addition to K (black) is taken as an example. explained. However, the present invention is widely applicable to a line-type inkjet printer that performs color printing using three or more chromatic colors.

DESCRIPTION OF SYMBOLS 1 Line type inkjet printer 10 Control unit 11 External interface part 14 Client terminal 15 External interface part 16 CPU
17 ROM
18 RAM
DESCRIPTION OF SYMBOLS 19 Input part 20 Output part 21 External storage device 22 Disk drive 50 Disk-shaped recording medium 90 CPU
91 ROM
92 RAM
93 External storage device 101 Scanner unit 102 Printer unit 103 Display 105 Paper feed unit 109 Paper discharge unit 110 Line head 110a Head block 160 Platen belt 161 Drive roller 162 Driven roller 500 Head holder 500a Head holder surface 500b Mounting opening CR1 Image forming path S Printing paper X Main scanning direction Y Sub-scanning direction Z Transport direction

Claims (4)

A print head that is provided with a plurality of nozzles and arranged so as to extend along the main scanning direction is arranged for each color at intervals in the sub-scanning direction orthogonal to the main scanning direction, and is conveyed in the sub-scanning direction Ink ejection amount control of an ink jet printer that forms a color image including at least two or more chromatic colors on the printing paper by landing ink droplets from corresponding nozzles of the line heads of the respective colors on the same pixel of the paper In the device
The printing paper based on at least one of the inclination of the extending direction of the line head with respect to the main scanning direction or the sub scanning direction and the inclination of the conveyance direction of the printing paper with respect to the main scanning direction or the sub scanning direction. Position misalignment information setting means for setting position misalignment information indicating the content of landing position misalignment between ink droplets of each color with respect to the same pixel;
A discharge amount correction table in which the landing position misalignment content and the ejection amount correction content of each color ink droplet for reducing the change in color tone of the pixel due to the landing position misalignment of the landing position misalignment content is stored. Storage means;
The discharge amount correction content of the ink droplets by the nozzles of the line head of each color is determined from the discharge amount correction table based on the positional shift information set in the positional shift information setting unit for each color and determined. A discharge amount correction means for correcting the discharge amount of ink droplets by each nozzle of the line head of each color in the correction content ;
The line head corresponding to each of three or more chromatic colors,
The ejection amount correction table includes the contents of the relative landing positions of chromatic ink droplets having a landing position deviation with respect to the printing paper with respect to chromatic ink droplets having no landing position deviation with respect to the printing paper. Is a table in which the discharge amount correction contents of the other chromatic ink droplets are associated with each other.
An ink discharge amount control apparatus. The ink discharge amount control apparatus according to claim 1, wherein the discharge amount correction table is a table in which the discharge amount correction content of the ink droplet with respect to the landing position deviation amount is larger for a color having a lower luminance value . The storage means stores the ejection amount correction table for each type of printing paper, and the ejection amount correction means uses the correction content determined from the ejection amount correction table corresponding to the type of printing paper for each color. The ink discharge amount control device according to claim 1 , wherein the discharge amount of ink droplets from each nozzle of the line head is corrected . The line head is configured by arranging a plurality of head blocks having a plurality of the nozzles in the main scanning direction, and the positional deviation information setting means sets the positional deviation information for each color in units of the head blocks. The discharge amount correcting means is a discharge amount correction content of the ink droplets determined based on the positional deviation information in units of the head block, and an ink droplet discharge amount by each nozzle of the line head of each color. The ink discharge amount control device according to claim 1 , wherein the ink discharge amount control device corrects the ink amount in units of the head block .

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